Fuel ignition and flame detection system



Nov. 3, 1970 L. H. WALBRIDGE 7' FUEL IGNITION AND FLAME DETECTION SYSTEMFiled March 1, 1968 3 Sheets-Sheet 1 3, 1970 H. 'WALBRIDGE ,5 8

FUEL IGNITION AND FLAME DETECTION SYSTEM Filed March 1, 1968 3Sheets-Sheet 2 ZyWIZWaZZIZ' Nov. 3, 1970 L. H. WALBRIDGE FUEL IGNITIONAND FLAME DETECTION SYSTEM Filed March 1968 r 3 Sheets-Sheet 312104222302 1392224222111 Walb?! by w a. 'mwz United States Patent "ice3,537,804 FUEL IGNITION AND FLAME DETECTION SYSTEM Lyman H. Walbridge,Ashland, Mass., assignor to Fenwal, Inc., Ashland, Mass. Filed Mar. 1,1968, Ser. No. 709,545 Int. Cl. F23n /08 US. Cl. 431-66 24 ClaimsABSTRACT OF THE DISCLOSURE A hot-wire ignition system including aphotoelectric element that senses igniter temperature by detecting theradiant energy level emitted by the igniter wire. A control circuitresponsive to the photoelectric element regulate both fuel flow to theburner and electrical energy flow to the igniter.

This invention relates generally to apparatus for igniting and detectingthe flames produced by fuel burners of the types, for example, used inhousehold and industrial gas appliances. More particularly, theinvention relates to an improved flame ignition and detection apparatusutilizing a hot wire igniter.

Because of the substantial disadvantages associated with continuouslyburning pilot flames, electric fuel igni tion has acquired increasedcommercial acceptance. The most common electrical ignition systemsutilize either spaced electrodes that produce flame igniting sparks orhot Wire igniters that are heated to fuel ignition temperature byelectrical current. A comparison of these two demonstrates severalsuperiorities of the hot wire igniter. For example, energization of hotwire igniters does not require either potentially dangerous highvoltages or high frequency alternating currents that generateinterference in certain frequency bands used for radio reception.Conversely, the primary drawback of the hot wire igniter and theprincipal reason for its relatively limited use is a susceptibility tothermal destruction at the high temperatures required for fuel ignition.

Various ignition control systems have been developed in attempts toalleviate the hot wire burnout problems. Basically, these systems haveemployed thermally responsive control elements or timing devices tolimit the maximum temperature and/or duty cycle to which the hot wire issubjected. Although providing some improvement, existing control systemshave not satisfactorily solved the nagging problem of limited igniterlife.

The fundamental deficiencies of prior control systems have been slowresponse and an inability to detect the maximum temperature existing onthe surface of the igniter wire. Because the thermal detectors such asthermocouples and thermistors used in previous systems respond primarilyto conduction and convection heating, they are relatively slow acting.This is undesirable since even extremely short periods of excessivetemperature can reduce the life of the ignited wire. In addition,because of the thermal sink provided by the detectors mass, the measuredtemperature of the directly adjacent igniter wire surface area portioncan be lower than the temperature of other igniter surfaces areaisolated thermally from the detector. Thus, maximum igniter surfacetemperature is not detected in all cases. This problem is accentuated inignition systems utilizing a wire igniter of the type commonly known asa glow coil. Since such coils of reasonable cost do not possess absoluteuniformity, temperature gradients of as much as 1000 F. can exist in asingle coil between those turns most closely and those least closelyspaced.

3,537,804 Patented Nov. 3, 1970 The object of this invention, therefore,is to provide an improved fuel ignition system which extends the life ofhot wire igniters.

CHARACTERIZATION OF THE INVENTION The invention is characterized by theprovision of a fuel ignition and flame detection system including a fuelhurner, a fuel flow regulator for regulating fuel flow to the burner, ahot wire igniter adapted for energization to ignite fuel discharged bythe burner, an energy regulator for regulating the flow of electricalenergy to the igniter, a photoelectric sensor positioned to detect thelevel of radiant energy emitted by the igniter, and a control systemresponsive to the photoelectric sensor and adapted to control the fueland energy regulators. The photoelectric sensor provides an extremelyfast measurement of substantially the hottest surface area portion onthe hot wire igniter.

One feature of the invention is the provision of a fuel ignition andflame detection system of the above type wherein the control system andenergy regulator prevent the flow of electrical energy to the hot wireigniter in response to detection by the photoelectric sensor of radiantenergy levels above a given maximum and the control system and fuel flowregulator produce fuel flow to the burner only in response to detectionof radiant energy levels above a given minimum. According to thisarrangement, both energy flow that would raise the temperature of thewire igniter to particularly harmful values above a predeterminedmaximum and unsafe fuel flow to the burner when the igniter is below apredetermined minimum temperature required to insure fuel ignition areeliminated.

Another feature of this invention is the provision of a system of theabove featured type wherein in response to heat generated by burningfuel the igniter wire is adapted to emit radiant energy at a level abovethe given minimum. Here, the igniter wire exercises the additionalfunction of a flame detector to both insure a continuous supply of fueland prevent electrical energization of the igniter in response to thepresence of a flame.

Another feature of the invention is the provision of a system of theabove featured type wherein the maximum radiant energy level at whichelectrical heat can be applied to the detector and the minimum energylevel required for fuel flow are equal. By controlling both the fuelflow regulator and the electrical energy regulator at the sametemperature, the desired regulation is obtained with a relatively simplecontrol system.

Another feature of this invention is the provision of a system of theabove featured type wherein the control system comprises an electricalrelay having a first set of contacts controlling the flow of electricalenergy to the igniter wire and a second set of contacts controlling theflow of fuel to the burner and wherein energization of the relayproduces actuation of the first contacts prior to actuation of thesecond contacts. This sequence of contact operation positivelyeliminates any simultaneous application of both electrical and flameenergy to the igniter.

Another feature of this invention is the provision of a system of thefirst featured type wherein the minimum radiant energy level requiredfor fuel flow is lower than the maximum radiant energy level that allowselectrical energy flow. By making the control system responsive todifferent radiant energy levels, the flow of electrical energy to theigniter can be maintained for some period after initiation of fuel flowto the burner thereby permitting the use of igniters having extremelylow mass.

Another feature of this invention is the provision of a system of theabove featured types including an auxiliary target adapted to be heatedby burning fuel discharged from the burner and to transmit radiantenergy to the photoelectric sensor. The use of an auxiliary target as aflame detector permits the system to operate as described above eventhough the igniter wire is cooled to relatively low temperatures duringfuel burning periods.

Another feature of this invention is the provision of a system of theabove featured types wherein the auxiliary target is positioned so as tobe heated to a higher energy radiating level by burning fuel dischargedfrom the burner than is the igniter wire. According to this arrangement,the igniter wire is positioned in a region permeated by fuel initiallydischarged from the burner but out of the primary region occupied byflames after ignition of the fuel While the auxiliary target is disposeddirectly in the fiame area.

Another feature of this invention is the provision of a system of thenext above featured type including a shield adapted to thermally isolatethe igniter wire from burning fuel. Because of the thermal shield, theigniter can be maintained at low temperatures during fuel burningperiods thereby prolonging its useful life.

These and other features and objects of the present invention willbecome more apparent upon a perusal of the following specification takenin conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic circuit diagram illustrating one embodiment of theinvention;

FIG. 2 is a schematic circuit diagram illustrating another embodiment ofthe invention;

FIG. 3 is a schematic side view of an igniter assembly embodiment of theinvention;

FIG. 4 is a schematic end view of the assembly shown in FIG. 3;

FIG. 5 is a schematic side view of another igniter assembly embodimentof the invention; and

FIG. 6 is a schematic top view of the assembly shown in FIG. 5.

Referring now to FIG. 1 there is shown the transformer 11 having theprimary winding 12 connected to the power input terminals 13 and 14,respectively, by lines 15 and 16. Connected in series with the secondarywinding 17 of the transformer 11 is the hot wire igniter 18 which ispreferably of the glow coil type. The igniter 18 is positioned so as toignite gaseous fuel fed to the burner 19 through the fuel line 21.

Disposed in the line 15 is the switch 22 having the contact 23 adaptedfor selective engagement with either the first contact 24 or the secondcontact 25. Engagement of movable contact 23 with the first contact 24connects the primary winding 12 across the input terminals 13 and 14while engagement with the second contact 25 connects the solenoid 26across the input terminals 13 and 14. The solenoid 26 actuates the valve27 in the fuel line 21. Also connected in line 15 is the overloadbreaker 28 having the heater element 29 and manually resettable warpswitch 31.

Connected in series between the lines 15 and 16 are the resistor 32, thediode 33 and the parallel combination of the voltage regulating diode 34and the capacitor 35. In parallel with the diode 34 and the capacitor 35are the series connected photocell 36 and the electromagnetic coil 37that operates the switch 22. The capacitor 38 is connected directlyacross the relay coil 37.

To initiate operation of the system, the manual switch 39 is closedenergizing the primary winding 12. The resultant current flow in thesecondary winding 17 produces resistive heating of the igniter coil 18until a predetermined temperature of, for example, 2400 F. is reached.At that temperature the igniter coil 18 emits a given level of radiantenergy which is transmitted to the photocell 36 through the hollowradiation shield tube 41. The selected characteristics of the photocell36 are such that, in response to the given radiant energy level, itsresistance is sufficiently lowered to permit energizing current flowthrough the relay coil 37 after a slight delay produced by the capacitor38. Energization of the coil 37 opens contacts 23 and 24 and closescontacts 23 and 25 thereby opening the circuit to the primary winding 12and closing the circuit to the electromagnetic valve solenoid 26. Thus,energy flow to the igniter 18 in the form of induced secondary currentis terminated and the fuel valve 27 is opened initiating fuel flow tothe burner 19. The fuel discharged by the burner 19 is ignited by theigniter 18 which, although deenergized, remains at a temperature abovethat required for ignition of the discharged fuel.

Heat generated by the burning fuel maintains the igniter coil 18 at anenergy radiating level above that required for the above describedresponse by the photocell 36. Therefore, the coil 37 remains energizedto both maintain fuel flow to the burner 19 and prevent electricalenergy flow to the igniter 18.

However, if for any reason, fuel ignition does not occur the ignitercoil 18 quickly cools to a temperature below the range detectable by thephotocell 36. The resultant increase in the photocell resistanceattenuates current flow through the winding 37 thereby causing switchcontacts 23 and 25 to open and switch contacts 23 and 24 to close.Accordingly, valve solenoid 36 is deenergized to close fuel valve 27 andinterrupt fuel flow and the transformer 11 is energized to resume flowof electrical energy to the igniter coil 18. Thus, the ignitionprocedure described above automatically repeats until fuel ignitionactually occurs. However, if ignition is not accomplished after apredetermined cycling period of, for example, 30 seconds the resistiveheating generated in the heater element 29 causes opening of the warpswitch 31 thereby terminating system operation. The switch 31 must thenbe manually reset to initiate a new ignition cycle.

Thus, the system automatically initiates fuel flow only when the igniter18 reaches a given temperature required for fuel ignition, interruptselectrical energy flow to the igniter 18 in response to detection ofthat given temperature, repeats the ignition step if ignition does notoccur, terminates the ignition procedure after a predetermined number ofunsuccessful cycles and terminates fuel flow in response to flameextinguishment. These operations provide two extremely desirableresults. First, the discharge of unburned fuel in dangerous amounts isprevented. Second, the igniter coil never is heated eithersimultaneously by both electrical energy and burning fuel or to above agiven maximum temperature by electrical energy alone. By so limiting itsthermal exposure, the useful life of the igniter coil 18 issubstantially lengthened. Furthermore, these advantages are uniquelyobtained by use of the radiant energy sensing photocell 36. Because thephotocell 36 detects instantaneously substantially the highesttemperature existing on the surface of the coil 18, the systemalleviates the danger of coil destruction because of undeteced excessivetemperatures existing in discrete sections of the coil.

Referring now to FIG. 2 there is shown another embodiment of theinvention having the primary winding 43 of the transformer 44 connectedto the input terminals 45 and 46, respectively, by lines 47 and 48.Connected in series with the secondary winding 49 of transformer 44 isthe igniter coil 51 which is positioned to ignite fuel supplied to theburner 52 through the fuel line 53. Between the input terminals 45 and46 are connected the silicon controlled rectifier 54 and the parallelcombination of the diode 55 and solenoid 56 that controls the fuelregulation valve 57 in the fuel line 53. Also connected in series acrossterminals 45 and 46 are the resistor 58, the diode 59, the photocell 61and the relay winding 62. The relay winding 62 operates the switchcontacts 63 that regulate flow of electrical energy through the primaryWinding 43. Each connected in parallel with both the photocell 61 andWinding 62 is the capacitor 65 and the voltage regulator diode 66. Thecapacitor 67 and the variable potentiometer 68 are each connected acrossthe relay winding 62. Coupled to the adjustable tap 69 of thepotentiometer 68 is the control electrode of the rectifier 64.

To initiate operation of this embodiment, the manual switch 71 is closedproducing current flow through the primary winding 43. The resultantsecondary current in winding 49' energizes the igniter coil 51. Inresponse to the increasing level of radiant energy received from theigniter coil 51 through the hollow radiation shield tube 72, theresistance of the photocell 61 decreases. At a predetermined minimumtemperature of, for example, 2200 F. the photocell resistance is loweredto a value that permits sufiicient current flow in the potentiometer 68to gate the rectifier 54. This produces energizing current flow throughthe solenoid 56 which opens the fuel regulation valve 57 to therebyprovide fuel fiow to the burner 52.

At a slightly higher maximum temperature of, for example, 2400 F. theradiant energy level emitted by the igniter coil 61 reduces theresistance of the photocell 61 sufliciently to permit energizing currentflow in the relay winding 62. The resultant opening of switch contacts63 interrupts current flow to the primary 43 and accordingly to theigniter coil 51. Even after termination of electrical energy flow to theigniter coil 51, the heat generated by the burning fuel maintains itstemperature above the energy radiation level required to maintainenergization of both the valve solenoid 56 and the relay winding 62.Therefore, the regulator valve 57 remains opened providing a continuousflow of fuel and the switch contacts 63 remain open preventingelectrical current flow to the coil 51.

If for any reason fuel ignition is not accomplished, the temperature ofthe igniter coil 51 quickly falls to an energy radiating level belowthat required for either energization of the relay winding 62 or forgating of the rectifier 54. Consequently, the solenoid 56 is deenergizedto close the fuel regulation valve 57 and the switch contacts 63 areclosed to resume current how to the transformer 44. Resultant energyflow to the igniter coil 51 again raises its temperature to above boththe minimum and maximum values required for the control operationsdescribed above. These ignition cycles continue until either ignitionoccurs or the heater element 73 in the overload breaker 74 causesopening of the warp switch 75. Initiation of a new ignition cyclerequires manual closing of the warp switch 75.

Thus, as in the embodiment of FIG. 1, the system shown in FIG. 2automatically initiates fuel flow only when the igniter 51 has reached apredetermined minimum temperature necessary for ignition, terminateselectrical energy flow to the igniter 51 in response to detection of agiven maximum temperature, repeats the ignition procedures if ignitiondoes not occur, terminates the ignition procedures after a predeterminednumber of cycles, and discontinues fuel flow in response to flameextinguishment. Therefore, the advantages discussed above in connectionwith FIG. 1 also are present here.

In addition, the separately activated rectifier 54 and relay winding 62permit independent control of the fuel regulator valve 57 and energyregulating switch contacts 63. Consequently, the fuel flow and energyflow functions can respond to different temperature levels as in theabove described operation wherein the temperature at which fuel how isinitiated is slightly lower than that at which current flow to the coil51 is interrupted. This important feature eliminates any period prior toignition wherein the coil -1 is actually cooling. Accordingly, the coil51 can possess relatively little mass which allows it to quickly reachignition temperature.

Referring now to FIGS. 3 and 4, there is shown a preferred igniterassembly 80 embodiment of the invention. Mounted on tabs 76 from one endof and axially aligned with the hollow radiation shield tube 81 is theceramic rod 77. The igniter coil 82 is supported by the rod 77 and hasends connected to the leads 78 in the insulator block 79. Mounted in theopposite end of the shield tube 6 81 is the photocell 83 which receivesradiant energy emitted by the igniter coil 82. Also supported by thetube 81 on the mounting bracket 84 is the target 85 aligned with thephotocell 83 and the igniter coil 82.

The igniter assembly is uniquely suited for use in the systemembodiments shown in FIGS. 1 and 2. After the igniter coil 82 has beenheated by electrical current to predetermined temperature levels, thephotocell 83 responds, as described above, to both initiate fuel flow tothe burner 86 and denergize the coil. Fuel is first discharged from theburner 86 in a pattern schematically illustrated by the dotted lines 87.That fuel engulfs the hot igniter 82 which prompts ignition. Because ofthe heat generated air currents, the resultant flame 88 is forced upwardand away from the deenergized igniter coil 82 which, therefore, cools tobelow ignition temperature. However, the flame 87 is in close heatexchanging relationship with the auxiliary target which is heated to atemperature substantially higher than that experienced by the ignitercoil 82. The material, for example Inconel, for the target 85 isselected so as to transmit to the photocell 83 at the temperatureproduced by the flame 87, a radiating energy level sufficient to bothmaintain fuel flow and prevent electrical current flow to the ignitercoil 82. Thus, in addition to insuring the various operating advantagesdescribed above, the igniter assembly 80 further reduces the thermalload on the igniter coil 82 during fuel burning periods. Because of thereduced thermal load, the life expectancy of a coil 82 is significantlylengthened.

FIGS. 5 and 6 illustrate another preferred igniter assembly 90embodiment of the invention. As shown, the igniter coil 91 and photocell92 are mounted in opposite ends of the hollow radiation shield tube 93.The tube 93 has one end portion longitudinally split forming the upwardprojecting ear members 94. Extending between the ear members 94 abovethe igniter coil 91 is the pin 95. The auxiliary target 96 has an upperend divided into outer leaves 97 rotatably supported by the pin andcenter leaf 98 attached to one end of the elongated bimetal element 99.Vertically restraining the opposite end of the bimetal element 99 is theclip 101. As shown, the target 96 has a curved shape conforming to theadjacent edge of the tube 93.

The igniter assembly 90 also is uniquely suited for use with the systemsshown in FIGS. 1 and 2. Energization of the igniter coil 91 to apredetermined minimum ignition temperature excites the photocell 92 toboth initiate fuel discharge from the burner 102 and interruptelectrical energy flow to the igniter coil. The burning fuel heats thebimetal element 99 which bows upward and moves the target 96 intocontact with the tube 93 as shown with dotted lines in FIG. 5. With thetarget in this position the igniter coil 91 is shielded from the burnerflame and is therefore maintained at relatively low temperatures duringfuel burning periods. However, the target 96 is fully heated by theflame to an energy radiating level suflicient to sustain excitation ofthe photocell 92 which responds by maintaining fuel flow to burner 102and preventing electrical energy flow to the igniter coil 91. The hottarget 96 also provides by conduction the heat necessary to maintain thebimetal element 99 in its bowed position. Thus, as in the embodiments ofFIGS. 3 and 4, the igniter assembly 90 insures reduced temperatures forthe igniter coil 91 during fuel burning periods thereby extending itsuseful life.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. For example, theindividual features shown in the various embodiments can be used incombinations other than those shown. Also, it is to be understood thatthe term hot wire igniter used in the specification embraces all typesof hot surface igniters including, for example, rods, bars, etc.Similarly, photoelectric sensing elements other than photocells can beused to detect the desired radiant energy levels. It is, therefore, tobe understood that within the scope of the appended claims the inventioncan be practiced otherwise than as specifically described.

What is claimed is:

1. A fuel ignition and flame detection system comprising a fuel burner,fuel flow regulator means for regulating the flow of fuel to saidburner, igniter means adapted to be electrically heated to fuel ignitiontemperature and to ignite fuel discharged by said burner, energyregulator means for regulating the flow of electrical energy to saidigniter means, photoelectric sensing means disposed to detect the levelof radiant energy emitted by said igniter means, and control meansactuated by said photoelectric sensing and adapted to control said fuelflow regulator means and said energy regulator means in response to thelevel of radiant energy emitted by said igniter means.

2. A fuel ignition and flame detection system according to claim 1wherein said control means and said energy regulator means are adaptedto prevent the flow of electrical energy to said ignition means inresponse to detection by said sensing means of radiant energy levelsemitted by said igniter means above a given maximum, and said controlmeans and said fuel flow regulator means are adapted to produce fuelflow to said burner only in response to detection by said sensing meansof radiant energy levels emitted by said igniter means above a givenminimum.

3. A fuel ignition and flame detection system according to claim 2wherein said igniter means is adapted to be heated to a radiating energylevel above said maximum and minimum levels by burning fuel dischargedby said burner.

4. A fuel ignition and flame detection system according to claim 3including an optical shield means adapted to transmit radiant energy tosaid photoelectric sensing means only along the rectilinear path joiningsaid igniter means and said sensing means and wherein said maximum andminimum radiant energy levels are equal.

5. A fuel ignition and flame detection system according to claim 4wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

6. A fuel ignition and flame detection system according to claim 5wherein said energy regulator means cornprises first electrical switchmeans, said fuel flow regulator means comprises an electrically operatedvalve and second electrical switch means, and said control meanscomprises electromagnetic means adapted to actuate said first and secondelectrical switch means so as to prevent current flow to said resistiveelement and open said valve in response to detection by said sensingmeans of said radiant energy level.

7. A fuel ignition and flame detection system according to claim 6wherein said first switch means is adapted for actuation to interruptcurrent flow prior to the actuation of said second switch means to opensaid valve.

8. A fuel ignition and flame detection system according ot claim 3wherein said energy regulator means and said fuel flow regulator meansare independently controlled by said control means and said minimumradiant energy level is lower than said maximum radiant energy level.

9. A fuel ignition and flame detection system according to claim 8wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

10. A fuel ignition and flame detection system according to claim 9wherein said control means comprises one electrical actuator responsiveto said sensing means and adapted to actuate said energy regulator meansin response to detection by said sensing means of said maximum radiantenergy level, and a second electrical actuator responsive to saidsensing means and adapted to actuate said fuel flow regulator inresponse to detection by said sensing means of said minimum radiantenergy level.

11. A fuel ignition and flame detection system according to claim 2wherein said igniter means is disposed so as to be directly contacted byfuel discharged from said fuel burner and including target means adaptedto be heated by burning fuel discharged by said burner and to supplyradiant energy to said sensing means.

12. A fuel ignition and flame detection system according to claim 11wherein said target is adapted for heating by said burning fuel to anenergy radiating level above said maximum and minimum levels.

13. A fuel ignition and flame detection system according to claim 12wherein said maximum and minimum radiant energy levels are equal.

14. A fuel ignition and flame detection system according to claim 13wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

15. A fuel ignition and flame detection system according to claim 12wherein said energy regulator means and said fuel flow regulator meansare independently controlled by said control means and said minimumradiant energy level is lower than said maximum radiant energy level.

16. A fuel ignition and flame detection system according to claim 15wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

17. A fuel ignition and flame detection system according to claim 12wherein said target means is adapted to be heated to a higher energyradiating level by burning fuel discharged by said burner than is saidigniter means.

18. A fuel ignition and flame detection system according to claim 17wherein said maximum and minimum radiant energy levels are equal.

19. A fuel ignition and flame detection system according to claim 18wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

20. A fuel ignition and flame detection system accord ing to claim 17wherein said energy regulator means and said fuel flow regulator meansare independently controlled by said control means and said minimumradiant energy level is lower than said maximum radiant energy level.

21. A fuel ignition and flame detection system according to claim 20wherein said ignition means comprises a resistive element adapted toconduct electrical heating current.

22. A fuel ignition and flame detection system according to claim 17including heat shield means adapted to shield said igniter means fromthe heat produced by burning fuel discharging from said burner.

23. A fuel ignition and flame detection system according to claim 22wherein said heat shield means is adapted for movement into a heatshielding position in response to heat generated by burning fueldischarging from said burner.

24. A fuel ignition and flame detection system according to claim 23wherein said target comprises said heat shield means.

References Cited UNITED STATES PATENTS 2,482,551 9/1949 Korsgren 431-663,151,661 10/1964 Matthews 43166 X 3,304,989 2/1967 Alexander et a1.431-79 X 3,434,788 3/1969 Wright 431-66 FOREIGN PATENTS 1,111,125 7/1961Germany.

EDWARD G. FAVORS, Primary Examiner US. Cl. X.R.

